Tungsten (Wolfram) - light-gray refractory metal. Density - 19.3 g/cm3, melting point - 3422 ° C. As the impurities contained in the tool steels and alloys. Pure tungsten is used in the light bulbs, electronics, cathodes, anodes and electronic devices.
Tungsten - heavy metal, melting point higher than the other metals (3422 °C). Tungsten can be welded and drawn out into thin threads.
Tungsten is a rare metal. Its content is 0.0055% in the ground, not presented in the sea water. However, the popularity of tungsten can compete with the other metals.
Tungsten was discovered by the famous Swedish chemist Carl Scheele. Pharmacist by profession, Scheele in his little lab had a lot of great research. He discovered oxygen, chlorine, barium, manganese. Shortly before his death, in 1781, Scheele - by this time a member of the Stockholm Academy of Sciences - found that the mineral tungsten is a salt of the then-unknown acid. Two years later, the Spanish chemists d'Eluyar brothers, working under the guidance of Scheele, were able to isolate from this mineral is a new element - tungsten, which was destined to revolutionize the industry.
Tungsten has practical importance as an alloying element. The main feature of tungsten as an alloying element is that it allows you to maintain the strength and hardness of the alloy at high temperatures.
Tungsten - the basis of hard alloys and superalloys, part of the wear-resistant alloys and tool steels. Tungsten and alloys used in producing of the parts of aircraft engines, and parts of the filament in the vacuum tubes. Also, due to the high density of tungsten is used for counterweights, artillery shells, bullets and bullet rotor gyros to stabilize ballistic missiles.
Modern High speed steel contain up to 18% of tungsten, molybdenum, chromium and cobalt. These alloys retain hardness at 800 ° C, while conventional steel start softing when heated only up to 200 °C.
At the beginning of XX century, tungsten filaments were used in light bulbs. Tungsten filament can bring the temperature up to 2200 ° C and gives significant light output. Tungsten is necessary in many areas of industry and everyday life.